The present invention relates to the field of lumber positioning or feeding systems to be used in saw mills, planing mills and the like in order to laterally displace lumber as it is being simultaneously advanced in the forward direction. In particular, the present invention is concerned with a lumber positioner apparatus for advancing lumber, which positioner comprises a vertically displaceable angling mechanism which may be selectively activated to cause lumber to be simultaneously displaced in a lateral direction, resulting in a vectorized movement of the lumber in order that the position of the lumber may be quickly and accurately controlled for further processing, such as cutting or trimming.
In general, feeding or positioning systems in the saw mill industry are known in the art, for example U.S. Pat. No. 2,657,784 to Stoker, U.S. Pat. No. 4,386,641 to Horn, U.S. Pat. No. 5,419,425 to Goater, U.S. Pat. No. 4,413,662 to Gregoire, et al., and U.S. Pat. No. 1,789,570 to Wahl. In addition, positioning systems which lateraly displace pieces of lumber as they are simultaneously being moved forward are also known. These positioning systems however use mechanical means disposed along the lateral edges of the system, which mechanical means physically push (i.e. mechanically act) against an end portions of the lumber. For example moveable gates may be disposed along the lateral edges of said systems, which movable gates may be, for example, hydraulicly driven to push against a side end of a piece of lumber, such that the lumber is simultaneously displaced sideways as it is being moved in a forward direction.
However, the use of mechanical gates which act on the side ends of lumber is inefficient and slow, and may potentially be damaging to the lumber. Further, the speed at which lumber may be fed by such systems is dependant on the speed at which the mechanical gates can operate, meaning that a piece of lumber must be fully laterally displaced before the next piece of lumber can be introduced into the system. As a result, the overall speed and efficiency of such systems is not very high. Further, the use of mechanical (moveable) gates acting on the side ends of the lumber may result in jamming of the lumber and the gates, which may cause damage to the lumber and/or to the gates, which may result in wastage of lumber or downtime of the machine. In addition, the moveable gates, in order to be efficient, require complex control systems and driving systems, therefore increasing the manufacturing, operational and maintenance costs of such systems. Finally, such systems are unsuitable for lateral displacement of curved or warped pieces of lumber, as the gate may pass underneath the warped end, which may cause the piece of lumber to fly up and over the machine, and may therefore create a safety problem.
Prior attempt have been made at developing a positioning system for simultaneous lateral and forward displacement of lumber without the use of positioning gates. For example, U.S. Pat. No. 4,753,335 to Goater discloses a positioner comprising a straight deck and an angled deck, which positioner comprises various mechanisms for first lowering, then raising the straight deck. Said positioner further comprises dual driving means for advancing the lumber forward, namely one associated with the angled deck and one associated with the straight deck. The dual driving means have the disadvantage that they must always be perfectly synchronized in order that a piece of lumber may be advanced at the same rate along the angled deck and along the straight deck. As the angled deck comprises a straight section and an angled section, this means that the relative forward speeds of a piece of lumber on the angled section and on the straight portions of the angle deck are not always the same, and further, not always the same in relation to the forward speed of the straight deck. If at any time the synchronization between the advancing means of the angled deck and that of the straight deck is upset, the positioning system of Goater may not function. Further, dual advancing means result in needless additional purchasing, operating and maintenance costs, and needlessly complicate the aparatus.
A further major disadvantage of this patent is the fact that, in order to effect the lateral displacement of a piece of lumber, each piece of lumber must be imparted with two sudden vertical impulses, i.e. each piece of lumber must be subjected to two (quick) vertically displacements. Namely, the lumber is displaced vertically (downwardly) when the straight deck which initially carries the lumber is lowered below the level of the angled deck, such that the lumber is no longer carried by the straight deck, but rather is carried only by the angled deck. This therefore causes the lumber to be suddenly dropped. Once on the angled deck, the lumber is displaced laterally as needed. Following the lateral displacement of the lumber, the straight deck is raised once again above the level of the angled deck, and in the process raises (i.e. vertically displaces) the lumber off of the angled deck, to be supported by the straight deck. This therefore causes the lumber to be suddenly raised.
The positioner of Goater therefore causes each individual piece of lumber to be vertically displaced twice, therefore doubling the potential for positional innacuracy of the lumber. Further, the use of a movable straight deck which may be raised upwardly to come into contact with a piece of lumber from underneath creates operational constraints as the impact of said movable deck hitting up against a piece of lumber from below may impart an impact force and an acceleration to said piece of lumber, and therefore can cause the piece of lumber to jump up. As a result, the speed at which the straight deck moves up may be limited, so as to reduce said impact force, and therefore may reduce the accuracy of the lateral positioning of the piece of lumber. The upward displacement of the straight deck may therefore be done slowly and smoothly, which naturally is ill-suited for an industrial application where speed and efficiency is vital. The positioner of U.S. Pat. No. 4,753,335 has not met with commercial or operational success.
A further disadvantage of U.S. Pat. No. 4,753,335 is the fact that two advancing means are required. In addition to needlessly duplicating the number of advancing mechanisms, (i.e. one in relation with the angled deck and one in relation with the straight deck), the advancing mechanism in relation to the straight deck must be specially adapted to allow for the straight deck to be lowered, then raised, while the advancing mechanism continues to operate (i.e. to turn) uninterruptedly. A further disadvantage of the '335 patent is the fact that the positioner comprises a number of long (i.e. along the whole length of the positioner) heavy straight decks, which have to be be fully lowered, then raised. The use of long straight decks needlessly increase the weight of the straight deck to be displaced, with a corresponding decrease in the speed and efficiency of the positioner. Further, the long and heavy straight deck also necessitates the use of powerful raising means, increasing costs.
It would be therefore advantageous to provide a lumber positioner having a vertically fixed forward displacement mechanism (means) and a vertically rotatable (displaceable) mechanism (means) for selective lateral displacement of lumber being advanced thereon.
It would be further advantageous to provide a lumber positioner wherein, during the lateral displacement phase of each piece of lumber, the piece of lumber is subjected to only one sudden vertical displacement.
It would be further advantageous to provide a lumber positioner wherein the pieces of lumber are first fed into the lumber positioned by placing them on the vertically rotatable angling mechanism, and wherein once the lumber has been laterally displaced the required or desired amount, a portion of the vertically rotatable angling mechanism is rotated downwardly such that the lumber is displaced downwardly and supported on the advancing means for further forward displacement.
It would be further advantageous to provide a lumber positioner which comprises only one drive means, namely a drive means associated with the vertically fixed lumber advancing means.
It would be further advantageous to provide a lumber positioner which comprises a non motorized vertically rotatable lateral displacement means.
It would be further advantageous to provide a lumber positioner which allows for a very high sped of operation.